Encouraged by rising sales of disposable diapers across Asia, Japanese chemical companies are investing in facilities to supply raw materials for the baby and adult care products.

Earlier this month, Zeon completed a more-than-$60 million expansion of a plant in Mizushima, Japan, that makes Quintac, a thermoplastic elastomer used to formulate pressure-sensitive adhesives. One of the big applications for such adhesives is fasteners for diapers, a point Zeon Chairman Naozumi Furukawa made at an opening ceremony.

Separately, both Toray Industries and Mitsui Chemicals Industries recently announced capacity expansions at facilities that produce non-woven fabrics for disposable diapers. Toray will increase output of polypropylene spunbond non-woven fabric in Gumi, South Korea. Mitsui will boost capacity at its site in Yokkaichi, Japan.

The announcements by the three companies come as another Japanese firm, Nippon Shokubai, is about to start up a new superabsorbent polymers plant in Himeji, Japan. Shokubai is the world’s top producer of the acrylic acid-based material, which is used mostly in diapers.

In announcing its project, Toray said Asian demand for disposable diapers is likely to grow at an annual rate of 9% in the coming years and that the supply of diaper raw materials is tight. In developed countries such as Japan, demand for adult diapers is the primary driver, Toray noted. But most of the growth in Asia is in developing countries, particularly China.

As Chinese parents become more affluent and urbanized, they are increasingly opting to put disposable diapers on their babies. As a result, the traditional open-crotch pants that make it more convenient for babies to do their business out in the open are becoming less commonplace on Chinese streets.